Tool bit retainer

ABSTRACT

A portable power tool comprising a housing having a motor disposed therein. The motor has an output rotary shaft interconnected with a tool bit supporting member by a gear train to transmit rotation to a tool bit. The motor also drives a reciprocating impacting mechanism adapted to strike the rear end of the tool bit and impart a longitudinal blow thereto. A novel retainer carried at the front of the housing prevents the tool bit from coming out of the housing and is manually movable to free the tool bit for removal and replacement.

United States Patent [72] Inventor Robert G. Moores, Jr.

Cockeysville, Md. [21] Appl. No. 71,635

[22] Filed Sept. 14, 1970 [45] Patented Jan. 11, 1972 [73] Assignee The Black and Decker Manufacturing Company Towson, Md.

[54] TOOL BIT RETAINER 10 Claims, 5 Drawing Figs.

[52] [1.8. CI 173/104, 279/19.7 [51] 1nt.Cl 825d 11/00, B23b 31/06 [50] Field of Search 173/104-1 l 1; 279/191, 19.2, 19.3, 19.6, 19.7, 90,

[56] References Cited UNITED STATES PATENTS 2,236,122 3/1941 Tuttle 279/19.7 3,161,242 12/1964 Etzkorn et a1. 173/109 2,236,121 3/1941 Tuttle 279/197 Primary Examiner-James A. Leppink Anomeys- Leonard Bloom, Joseph R. Slotnik and Edward D.

Murphy ABSTRACT: A portable power tool comprising a housing having a motor disposed therein. The motor has an output rotary shaft interconnected with a tool bit supporting member by a gear train to transmit rotation to a tool bit. The motor also drives a reciprocating impacting mechanism adapted to strike the rear end of the tool bit and impart a longitudinal blow thereto. A novel retainer carried at the front of the housing prevents the tool bit from coming out of the housing and is manually movable to free the tool bit for removal and replacement.

PMENTEB mu 1 :972 35335 4 INVENIOR ROBERT G. MOORES,JR

ATTORNEY TOOL BIT RETAINER SUMMARY OF THE INVENTION The present invention is directed to an improved tool bit retainer for a rotary hammer, i.e., one in which the tool bit is rotated and longitudinally impacted against a work surface. The retainer is disposed on the front of the tool housing and surrounds the bit and is tumable from a first position where the bit is retained in the tool housing to a second position where the bit may be removed from the housing. The retainer advantageously utilizes frictional torque developed by the rotating bit to hold it in the first position and obviates the need for any detents, fasteners, or the like. Furthermore, the retainer embodies simplicity and is reliable in use.

Main objects of the present invention, therefore, are to provide an improved tool bit retainer construction for a rotary hammer which securely retains the tool bit in position within the tool, is readily movable from a bit-retaining to a bit-releasing position, which requires no fasteners and/or detents or special tools to release or secure it in position, and which utilizes forces developed in the use of the tool to hold it in a tool bit retaining position.

Further important objects of the present invention are to provide a novel retainer construction of the above character which is relatively inexpensive to manufacture, rugged in construction, and reliable in use.

Other objects and advantages of the invention will become more apparent from a consideration of the detailed description to follow taken in conjunction with the drawings annexed hereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a elevational view of a rotary hammer embodying the present invention;

FIG. 2 is an enlarged sectional view of a portion of FIG. 1 and showing the retainer in the bit-retaining position;

FIG. 3 is an end view of the structure of FIG. 2;

FIG. 4 is a view similar to FIG. 3 showing the retainer in the bit-releasing position; and

FIG. 5 is a perspective view of FIG. 4 shown with the bit removed for clarity.

BROAD STATEMENT OF THE INVENTION Broadly described, the present invention relates to a rotary hammer of the type which includes a housing having a motor disposed therein, tool bit support means rotatably disposed in said housing and adapted to slidably and nonrotatably support a tool bit, transmission means interconnecting said motor and said tool bit supporting means whereby to rotate said tool bit in a first direction, impacting means driven by said motor and adapted to deliver longitudinal reciprocating blows to said tool bit; the improvement which comprises a tool bit retainer on said housing, said tool bit extending loosely past and engageable with said retainer, said retainer being tumable on said housing from a first position to a second position, said retainer and said tool bit having generally radial abutment means cooperable to prevent withdrawal of said tool bit from said housing when said retainer is in said first position, said tool bit being freely removable from said housing when said retainer is in said second position, positive stop means preventing turning movement of said retainer in said first direction past said first position.

In another aspect, the present invention relates to a rotary hammer of the type which includes a housing having a motor disposed therein, tool bit support means rotatably disposed in said housing and adapted to slidably and non rotatably support a tool bit, transmission means interconnecting said motor and said tool bit supporting means whereby to rotate said tool bit, impacting means driven by said motor and adapted to deliver longitudinal reciprocating blows to said tool bit, the improvement which'comprises a tool bit retainer on said housing, said retainer including an annular member turnably supported upon said housing and having a radial wall provided with an opening therein, said tool bit extending loosely through said opening for all rotative positions of said'retainer and having a radial shoulder slightly smaller in diameter than said opening, positive stop means preventing turning movement of said retainer in one direction from the first position where said radial wall overlays at least a portion of said radial flange, said retainer being tumable in another direction opposite said one direction from said first position to a second position where said radial flange is aligned with said opening, whereby said tool bit may be removed from said support means when said retainer is in said second position.

In another aspect, the present invention relates to a tool bit retainer for a power tool of the type which rotates a tool bit and delivers axial impact blows thereto, said power tool including a housing, said retainer comprising a cup-shaped member having a radial peripheral flange'rotatably retained upon said housing, said tool bit having a radial shoulder, said member having a aperture sized larger than said radial shoulder on said tool bit and adapted to be aligned and misaligned with said radial shoulder in first and second rotative positions, respectively, of said retainer upon said housing, cooperable means on said retainer and said housing positively preventing rotative movement of said retainer in one direction past said second position, said bit adapted to develop frictional torque on said retainer tending to turn in said one direction during operation of said tool.

DETAILED DESCRIPTION Referring now more specifically to the drawings, an illustrative, electric powered, rotary hammer embodying the present invention is illustrated generally at 11 in FIG. I and is seen to include interconnected motor and end housings l3, 15. The motor housing 13 has an end handle 17 rigid therewith on which is mounted an on-ofitrigger switch 19 and from which depends a conventional line cord 21. It will be appreciated that the housing l3, l5 and the handle 17 may be constructed from a die cast aluminum alloy or may be molded from a suitable glass fiber material as is customary in the art.

The rotary hammer 11 is provided with an electric motor 23 located within the lower portion of the motor housing 13. The motor 23 includes an armature shaft 25 supported adjacent its forward end by a bearing 27 and has pinion teeth 29 formed thereon. A large gear 31, fixed to a shaft 33 supported fore and aft in the end housing 15 by bearings 35, 37 is driven by the pinion teeth 29, and another gear 39 fixed to the shaft 33 drivingly engages an output gear 41 fixed to a tool bit supporting collar 43 The collar 43 is supported fore and aft within the end housing 15 by bearings 45, 47 and is provided with a stepped through bore 49. A tool bit 51 extends slidably into the bore 49 and has a hexagonal cross-sectional rear shank 53 slidably and nonrotatably received in a complimentary configured portion 55 of the bore 49. Thus, when the motor 23 is energized, the collar 43 is rotatably driven through gears 29, 31,39, 41 and turns the tool bit 61.

In addition to being rotated, longitudinal impact blows are delivered to the rear end of the bit 51. These blows are delivered by a ram 57 which has its forward end slidably disposed within a bore 59 in the rear of the bitsupporting collar 43. The ram 57 is keyed within the collar 43 by balls 63. In addition, the rear end (not shown) of the ram 57 has cam lift means (not shown) cooperating with nonrotatably cam means (not shown) fixed to a barrel 61 secured to a gear case cover 62 by screws 64. A coil spring (not shown) normally biases the ram 57 in a forward or right-hand direction as seen in FIG. 2. The ram 57 is moved in a rearward or left-hand direction, as seen in this figure against the force of the coil spring by means of the cooperating cam lift means on the ram 57 and barrel 61 when the collar 43 rotates. Thus, when the motor 23 is energized and the collar 43 rotated, the ram 57 is gradually cammed rearwardly, or toward the left as seen in FIG. 2 and thereafter the ram 57 is driven forwardly, or toward the right as seen in FIG. 2, under the force of the soil spring and delivers an impact blow to the rear end of the tool bit shank 53. Thus, during operation of the motor 23, the tool bit 51 is rotated and has longitudinal or axial impact blows delivered thereto.

In the normal use of the rotary hammer 11, the forward or working end of the bit 51 is pressed against a work surface so that during rotation and impacting the bit 51 is prevented from coming out the front of the end housing 15. However, when the tool bit 51 is not in engagement with a work surface, the impact blows delivered to the bit by the ram 57 tend to drive the bit 51 out of the front of the end housing 15. This situation can occur if the tool is turned on before the tool bit 51 is engaged with the work surface, or if the tool is moved away from the work surface before the trigger 19 is released.

To prevent the bit from coming out of the housing, it is customary to provide a retainer on the front of the end housing 15. However, these retainer, which generally include springs, are relatively bulky and expensive, and contribute significantly to the overall cost and axial length of the tool.

In accordance with the present invention, an improved retainer is provided which is relatively short and compact, near and aesthetically pleasing in appearance, inexpensive and reliable, and is relatively simple to use. This retainer is illustrated generally at 67 and is seen to include a cup-shaped member 69 which extends through an aperture 77 in a plate 73 fixed to the end housing by screws 75. The member 69 is turnably supported by the plate 73 and has a radial peripheral flange 71 trapped between the plate 73 and a resilient washer 74 or the like. The outer end of the cup 69 has a radial wall 78 provided with an aperture 79 sized larger than the diameter of a radial flange 81 or the tool bit 51. The aperture 79 is eccentric with respect to the axis of the tool bit 51 so that in one rotative position of the cup 69, shown in FIGS. 2 and 3, the wall overlays a part of the flange 81 of the tool bit 51 and prevents the bit 51 from coming out of the housing 15. In another rotative position of the retainer cup 69, shown in FIG. 4, the aperture is substantially concentric with the axis of the bit 51 and the flange 81 and in this position the bit 51 can easily be removed and/or replaced from the housing 15.

The retainer cup 69 is provided with a radial projection 83 adapted to engage the screws 75 and limit turning movement of the cup 69. Conveniently, the projection 83 engages with one screw 75 when the cup is in the first or bit retaining position, shown in FIG. 3, and engages with the other screw 75 when the cup is in the tool bit releasing position, shown in FIG. 4. This makes it relatively easy for the operator to position the cup 69 accurately in either the bit retaining or bit releasing position.

In addition, the retainer 67 05 the present invention utilizes frictional torque developed by the tool bit 51 thereon during operation of the device 11 to help hold the cup 69 in the retaining position. Thus, it will be appreciated that the tool bit 51 rotates in a counterclockwise direction as seen in FIGS. 3 and 4 during normal operation of the rotary hammer 11, some contact will likely occur between the surface of the bit 51 and the edge of the retainer cup 69 at the aperture 79. This engagement tends to cause the cup 69 to turn similarly in a counterclockwise direction as seen in these figures and helps hold the projection 83 against the screw 75 as seen in FIG. 3. Thus, there is no need for additional fasteners, detents or the like to hold the cup 69 in the bit retaining position. In addition, the resilient washer 74 imposes a frictional force on the cup member flange 71 to resist unintended rotation of the cup 69 as a result of vibrational forces arising during normal operation of the tool 11.

When it is desired to remove and/or replace a tool bit 51, the operator turns the tool 11 off, whereupon the retainer cup 69 can easily be turned in a clockwise position as seen in FIG.- 3 and 4, from the FIG. 3 position to the FIG. 4 position, whereupon the tool bit 51 is thereafter easily removed from the housing-l5l When the tool bit 51 is replaced, the retainer cup 69 is manually turned back to the FIG. 3 position. To

facilitate easy manual manipulation of the cup 69, its outer surface may be provided with serrations as seen in FIG. 5.

By the foregoing, there has been provided a novel tool bit retainer construction for a rotary hammer calculated to fulfill the inventive objects hereinabove set forth, and while a preferred embodiment has been demonstrated described above in detail, it will be appreciated that various additions, substitutions, observations, and omissions may be made thereto without departing from the spirit of the invention.

I claim:

1. A rotary hammer of the type which includes a housing having a motor disposed therein, tool bit support means rotatably disposed in said housing and adapted to slidably and nonrotatably support a tool bit, transmission means interconnecting said motor and said tool bit supporting means whereby to rotate said tool bit in a first direction, impacting means driven by said motor and adapted to deliver longitudinal reciprocating blows to said tool bit, the improvement which comprises a tool bit retainer on said housing, said tool bit extending loosely past and engageable with said retainer, said retainer being tumable on said housing from a first position to a second position, said retainer and said tool bit having generally radial abutment means cooperable to prevent withdrawal of said tool bit from said housing when said retainer is in said first position, said tool bit being freely removable from said housing when said retainer is in said second position, positive stop means preventing turning movement of said retainer in said first direction past said first position.

2. A tool bit retainer for a power tool of the type which rotates a tool bit and delivers axial impact blows thereto, said power tool including a housing, said retainer comprising a cup-shaped member having a radial peripheral flange rotatably retained upon said housing, said tool bit having a radial shoulder said member having an aperture sized larger than said radial shoulder on said tool bit and adapted to be aligned and misaligned with said radial shoulder in first and second rotative positions, respectively, of said retainer upon said housing, cooperable means on said retainer and said housing positively preventing rotative movement of said retainer in one direction past said second position, said bit adapted to develop frictional torque on said retainer tending to turn in said one direction during operation of said tool.

3. A retainer as defined in claim 2 wherein said cooperable means prevents movement of said retainer in the other direction past said second position.

4. A retainer as defined in claim 2 wherein said cooperable means includes a radial projection on said retainer.

5. A rotary hammer of the type which includes a housing having a motor disposed therein, tool bit support means rotatably disposed in said housing, and adapted to slidably and nonrotatably support a tool bit, transmission means interconnecting said motor and said tool bit supporting means whereby to rotate said tool bit, impacting means driven by said motor and adapted to deliver longitudinal reciprocating blows to said tool bit, the improvement which comprises a tool bit retainer on said housing, said retainer including an annular member turnably supported upon said housing and having a radial wall provided with an opening therein, said tool bit extending loosely through said opening for all rotative positions of said retainer and having a radial shoulder slightly smaller in diameter than said opening, positive stop means preventing turning movement of said retainer in one direction from a first position where said radial wall overlays at least a portion of said radial flange, said retainer being tumable in another direction opposite said one direction from said first position to a second position where said radial flange is aligned with said opening, whereby said tool bit may be removed from said support means when said retainer is in said second position.

6. The improvement as defined in claim 5 wherein said stop means includes a radial projection on said retainer cooperably with means on said housing and to prevent movement of said retainer past said first position.

retainer includes a radial peripheral flange turnably trapped between said housing and a plate fixed thereto by screws, said screws forming the abutment means on said housing.

10. The improvement as defined in claim 9 which further includes a resilient washer frictionally engaging said flange to resist unintended turning of said retainer II! III i 

1. A rotary hammer of the type which includes a housing having a motor disposed therein, tool bit support means rotatably disposed in said housing and adapted to slidably and nonrotatably support a tool bit, transmission means interconnecting said motor and said tool bit supporting means whereby to rotate said tool bit in a first direction, impacting means driven by said motor and adapted to deliver longitudinal reciprocating blows to said tool bit, the improvement which comprises a tool bit retainer on said housing, said tool bit extending loosely past and engageable with said retainer, said retainer being turnable on said housing from a first position to a second position, said retainer and said tool bit having generally radial abutment means cooperable to prevent withdrawal of said tool bit from said housing when said retainer is in said first position, said tool bit being freely removable from said housing when said retainer is in said second position, positive stop means preventing turning movement of said retainer in said first direction past said first position.
 2. A tool bit retainer for a power tool of the type which rotates a tool bit and delivers axial impact blows thereto, said power tool including a housing, said retainer comprising a cup-shaped member having a radial peripheral flange rotatably retained upon said housing, said tool bit having a radial shoulder said member having an aperture sized larger than said radial shoulder on said tool bit and adapted to be aligned and misaligned with said radial shoulder in first and second rotative positions, respectively, of said retainer upon said housing, cooperable means on said retainer and said housing positively preventing rotative movement of said retainer in one direction past said second position, said bit adapted to develop frictional torque on said retainer tending to turn in said one direction during operation of said tool.
 3. A retainer as defined in Claim 2 wherein said cooperable means prevents movement of said retainer in the other direction past said second position.
 4. A retainer as defined in claim 2 wherein said cooperable means includes a radial projection on said retainer.
 5. A rotary hammer of the type which includes a housing having a motor disposed therein, tool bit support means rotatably disposed in said housing, and adapted to slidably and nonrotatably support a tool bit, transmission means interconnecting said motor and said tool bit supporting means whereby to rotate said tool bit, impacting means driven by said motor and adapted to deliver longitudinal reciprocating blows to said tool bit, the improvement which comprises a tool bit retainer on said housing, said retainer including an annular member turnably supported upon said housing and having a radial wall provided with an opening therein, said tool bit extending loosely through said opening for all rotative positions of said retainer and having a radial shoulder slightly smaller in diameter than said opening, positive stop means preventing turning movement of said retainer in one direction from a first position where said radial wall overlays at least a portion of said radial flange, said retainer being turnable in another direction opposite said one direction from said first position to a second position where said radial flange is aligned with said opening, whereby said tool bit may be removed from said support means when said retainer is in said second position.
 6. The improvement as defined in claim 5 wherein said stop means includes a radial projection on said retainer cooperably with means on said housing and to prevent movement of said retainer past said first position.
 7. The improvement as defined in claim 6 wherein said tool bit imparts frictional torque to said retainer tending to rotate it towards said first position.
 8. The improvement as defined in claim 6 wherein said stop means and said housing prevents movement of said retainer past said second position.
 9. The improvement as defined in claim 5 wherein said retainer includes a radial peripheral flange turnably trapped between said housing and a plate fixed thereto by screws, said screws forming the abutment means on said housing.
 10. The improvement as defined in claim 9 which further includes a resilient washer frictionally engaging said flange to resist unintended turning of said retainer. 